Tropical
Highlights - September 2017

Sea surface
temperatures (SSTs) during September 2017 remained near-average over the
central equatorial Pacific and below-average across
the eastern equatorial Pacific (Fig. T18, Table T2). The latest
monthly
Niņo indices were +0.0°C for the Niņo 4
region, -0.4°C
for the Niņo 3.4 region, and -0.7°C for the Niņo 1+2 region (Table
T2, Fig. T5). The depth of the oceanic thermocline
(measured by the depth of the 20°C isotherm) was below-average over much of the
eastern equatorial Pacific (Figs. T15, T16), and
the corresponding sub-surface temperatures were 1-3°C below average (Fig. T17).

Also during September, the lower-level
trade winds were enhanced across the western equatorial Pacific and the
upper-level winds were near average over much of the equatorial Pacific (Table T1, Figs. T20, T21). Meanwhile, convection
was enhanced over Indonesia and suppressed over the central equatorial Pacific (Figs. T25, E3). Collectively, these oceanic and
atmospheric anomalies are consistent with ENSO-neutral conditions.

For the latest status of the ENSO
cycle see the ENSO Diagnostic Discussion at:
http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/enso_advisory/index.html